为了更准确地模拟小当量梯恩梯(TNT)水下爆炸的气泡脉动过程,对气泡脉动数值模拟结果的影响因素进行探究。应用Autodyn有限元软件对13 g TNT水下爆炸进行数值模拟发现,使用TNT的JWL状态方程和水的多项式状态方程及其参数,且网格尺寸为5...为了更准确地模拟小当量梯恩梯(TNT)水下爆炸的气泡脉动过程,对气泡脉动数值模拟结果的影响因素进行探究。应用Autodyn有限元软件对13 g TNT水下爆炸进行数值模拟发现,使用TNT的JWL状态方程和水的多项式状态方程及其参数,且网格尺寸为5 mm、边界条件为压力流出时,数值模拟结果与经验公式计算得到的理论值间误差较小。改变网格尺寸和边界条件,发现在满足工程精度前提下,网格尺寸为1 mm且边界条件为压力流出时数值模拟结果较准确,其中气泡脉动周期以及气泡膨胀最大半径的数值模拟结果与经验公式间的误差仅为3.61%和1%.对10 g TNT开展水下爆炸试验,并基于以上条件对试验进行数值模拟。发现各测点处试验结果与数值模拟结果间的误差较小,进一步验证了气泡脉动数值模拟的真实性和准确性。对10 g TNT炸药在不同爆炸深度下的气泡脉动进行数值模拟,得到了气泡脉动周期T和气泡膨胀最大半径Amax与爆炸深度H之间的关系:T=23.2e^(-H/92.93)+39.76e^(-H/12.74)+2.08,Amax=0.12e^(-H/324.67)+0.16e^(-H/14.85)+0.07.展开更多
Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambiq...Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambique's continental margin is considered of great significance to rebuild Gondwana land and understand its movement mode. Along these lines, in this work, the initial Moho was fit using the known Moho depth from reflection seismic profiles, and a 3D multi-point constrained gravity inversion was carried out. Thus, highaccuracy Moho depth and crustal thickness in the study area were acquired. According to the crustal structure distribution based on the inversion results, the continental crust at the narrowest position of the Mozambique Channel was detected. According to the analysis of the crustal thickness, the Mozambique ridge is generally oceanic crust and the COB of the whole Mozambique continental margin is divided.展开更多
The seasonal change in depths of the frozen and thawed soils within their active layer is reduced to a moving boundary problem, which describes the dynamics of the total ice content using an independent mass balance e...The seasonal change in depths of the frozen and thawed soils within their active layer is reduced to a moving boundary problem, which describes the dynamics of the total ice content using an independent mass balance equation and treats the soil frost/thaw depths as moving (sharp) interfaces governed by some Stefan-type moving boundary conditions, and hence simultaneously describes the liquid water and solid ice states as well as the positions of the frost/thaw depths in soil. An adaptive mesh method for the moving boundary problem is adopted to solve the relevant equations and to determine frost/thaw depths, water content and temperature distribution. A series of sensitivity experiments by the numerical model under the periodic sinusoidal upper boundary condition for temperature are conducted to validate the model, and to investigate the effects of the model soil thickness, ground surface temperature, annual amplitude of ground surface temperature and thermal conductivity on frost/thaw depths and soil temperature. The simulated frost/thaw depths by the model with a periodical change of the upper boundary condition have the same period as that of the upper boundary condition, which shows that it can simulate the frost/thaw depths reasonably for a periodical forcing.展开更多
The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artifi-cial boundary condition.The artificial boundary is usually selected as a circle or spherical s...The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artifi-cial boundary condition.The artificial boundary is usually selected as a circle or spherical surface to solve various types of fields,such as sound waves or electromagnetic waves,provided that the considered domain is infinite or unbounded in all directions.However,the substantial wave motion is considered in water of finite depth,that is,the fluid domain is bounded vertically but unbounded horizon-tally.Thus,the DtN boundary condition is given on an artificial cylindrical surface,which divides the water domain into an interior and exterior region.The boundary integral equation is adopted to implement the present model.In the case of a floating cylinder,the results of hydrodynamic coefficients of a chamfer box are discussed.展开更多
文摘为了更准确地模拟小当量梯恩梯(TNT)水下爆炸的气泡脉动过程,对气泡脉动数值模拟结果的影响因素进行探究。应用Autodyn有限元软件对13 g TNT水下爆炸进行数值模拟发现,使用TNT的JWL状态方程和水的多项式状态方程及其参数,且网格尺寸为5 mm、边界条件为压力流出时,数值模拟结果与经验公式计算得到的理论值间误差较小。改变网格尺寸和边界条件,发现在满足工程精度前提下,网格尺寸为1 mm且边界条件为压力流出时数值模拟结果较准确,其中气泡脉动周期以及气泡膨胀最大半径的数值模拟结果与经验公式间的误差仅为3.61%和1%.对10 g TNT开展水下爆炸试验,并基于以上条件对试验进行数值模拟。发现各测点处试验结果与数值模拟结果间的误差较小,进一步验证了气泡脉动数值模拟的真实性和准确性。对10 g TNT炸药在不同爆炸深度下的气泡脉动进行数值模拟,得到了气泡脉动周期T和气泡膨胀最大半径Amax与爆炸深度H之间的关系:T=23.2e^(-H/92.93)+39.76e^(-H/12.74)+2.08,Amax=0.12e^(-H/324.67)+0.16e^(-H/14.85)+0.07.
基金The National Natural Science Foundation of China under contract No. 42076078China–Mozambique Joint Cruise under contract No. GASI-01-DLJHJ-CM。
文摘Mozambique's continental margin in East Africa was formed during the break-off stage of the east and west Gondwana lands. Studying the geological structure and division of continent-ocean boundary(COB) in Mozambique's continental margin is considered of great significance to rebuild Gondwana land and understand its movement mode. Along these lines, in this work, the initial Moho was fit using the known Moho depth from reflection seismic profiles, and a 3D multi-point constrained gravity inversion was carried out. Thus, highaccuracy Moho depth and crustal thickness in the study area were acquired. According to the crustal structure distribution based on the inversion results, the continental crust at the narrowest position of the Mozambique Channel was detected. According to the analysis of the crustal thickness, the Mozambique ridge is generally oceanic crust and the COB of the whole Mozambique continental margin is divided.
基金the National Basic Research Program(Grant No.2005CB321703)the Knowledge Innovation Project of Chinese Academy of Sciences(Grant Nos.KZCX2-yw-126-2,KZCX2-yw-217)the Chinese Coordinated Observation and Prediction of the Earth System project(Grant No.GYHY20070605)
文摘The seasonal change in depths of the frozen and thawed soils within their active layer is reduced to a moving boundary problem, which describes the dynamics of the total ice content using an independent mass balance equation and treats the soil frost/thaw depths as moving (sharp) interfaces governed by some Stefan-type moving boundary conditions, and hence simultaneously describes the liquid water and solid ice states as well as the positions of the frost/thaw depths in soil. An adaptive mesh method for the moving boundary problem is adopted to solve the relevant equations and to determine frost/thaw depths, water content and temperature distribution. A series of sensitivity experiments by the numerical model under the periodic sinusoidal upper boundary condition for temperature are conducted to validate the model, and to investigate the effects of the model soil thickness, ground surface temperature, annual amplitude of ground surface temperature and thermal conductivity on frost/thaw depths and soil temperature. The simulated frost/thaw depths by the model with a periodical change of the upper boundary condition have the same period as that of the upper boundary condition, which shows that it can simulate the frost/thaw depths reasonably for a periodical forcing.
文摘The present paper focuses on the wave radiation by an oscillating body with six degrees of freedom by using the DtN artifi-cial boundary condition.The artificial boundary is usually selected as a circle or spherical surface to solve various types of fields,such as sound waves or electromagnetic waves,provided that the considered domain is infinite or unbounded in all directions.However,the substantial wave motion is considered in water of finite depth,that is,the fluid domain is bounded vertically but unbounded horizon-tally.Thus,the DtN boundary condition is given on an artificial cylindrical surface,which divides the water domain into an interior and exterior region.The boundary integral equation is adopted to implement the present model.In the case of a floating cylinder,the results of hydrodynamic coefficients of a chamfer box are discussed.
